Chemically modified film covering for apertured smoking product wrapper

ABSTRACT

The disclosure relates to a film covering for a smoking product wrapper, such as a cigarette wrapper. The wrapper is either porous, or is deliberately perforated with vents or apertures. These openings or vents are covered with a polymeric film made of a polyalkalene oxide, polyvinyl alcohol or copolymer thereof containing butadiene or isoprene units as well as natural gums and resins that has been submitted to a degradation operation. The degradation is chemically produced utilizing an oxidizer/free-radical generator. The degradation facilitates and expedites the removal of film over the apertures by smoke components so that air is permitted to dilute the smoke during the later stages of smoking.

United States Patent Tamol et a1. i

[451 Dec. 12, 1972 [72] Inventors: Ronald A. Tamoltbeo F. Meyer,

both of Richmond, Va.

[73] Assignee: Philip Morris Incorporated, New

York, N.Y.v

[22] Filed: July 6, 1971 [21] Appl. No.: 160,059

[52] us. Cl. ..131/15 s, 131/9 [51] Int. Cl. ..A24d 1/02, D2 lh 5/16 [58] Field ofSeareh ..131/2, 9,15,17,140-144 [56] References Cited UNITED STATES PATENTS 2,836,183 5/1958 Fay et al ..l3l/4 3,473,535 10/1969 Stahly ..l3i/15B 3,526,904 9/1970 Tamol l 3 1/15 B Primary Examiner-Melvin D. Rein Attorney-Elmer R. l'lelferich et a1.

[57] ABSTRACT The disclosure relates to a film covering for a smoking product wrapper, such as a cigarette wrapper. The

wrapper is either porous, or is deliberately perforated with vents or apertures. These openings-or vents are covered with a polymeric film made of a polyalkalene oxide, polyvinyl alcohol or copoly'mer thereof containing butadiene or isoprene units as well as natural gums and resins that has been submitted to a degradation operation. The degradation is chemically produced utilizing an oxidizer/free-radical generator. The degradation facilitates and expedites the removal of film over the apertures by smoke components so that air is permitted to dilute the smoke during the later stages of smoking.

5 Claims, No Drawings CI-IEMICALLY MODIFIED FILM COVERING FOR APERTURED SMOKING PRODUCT WRAPPER BACKGROUND OF THE INVENTION It has been known that the amount of smoke delivered to the smoker of acigarette can be lowered, without increasing the resistance-to-draw of the cigarette, by increasing the proportion of air which is drawn in with the smoke behind the burning coal. It is also known that additional air can be provided with the smoke by using a very porous paper as the wrapper for the tobacco or by making perforations in the paper. In this way a greater proportion of the combustion products are dissipated to the atmosphere in the intervals between puffing. Cigarettes have also been made wherein ventilation holes have been included in.the paper or in the overtipping surrounding the filter plug of a filter cigarette. In addition, various methods have been described for the smoker to select the degree of ventilation before smoking.

None of the above-described methods have been completely satisfactory, however. Cigarettes which have. been ventilated to any significant degree have been characterized by many smokers as being thin, tastelessb or not satisfying.

Among the various proposals made to provide a degree of ventilation may be mentioned a patent to Swain, U.S. Pat. No. 2,754,828 disclosing the use of covered apertures in a non-combustible cigarette sheet, the covering over the apertures being combustible and thus providing for heat-opening of the apertures during the burning of the tobacco. The essential purpose of this patent is to supply sufficient air through the apertures to support combustion when they are opened by the heat of burning tobacco. I

A patent to Figge, US. Pat. No. 2,992,647, also teaches the use of a perforated or vented cigarette wrapper, with the apertures being closed with .a sealing material selected to melt or sublime at low temperatures but actually a short distance in advance of the burning area, the patentees purpose and objective being to lower the combustion temperature of the burning cigarette with air intake through the apertures upon the approach of the hot coal to the vent holes. Figge, therefore, selected sealants that would melt or sublime close to the burning area, mentioning polyethylene or cellulose sealant compounds, that is said to dissipate at 50C. to 100C. but also mentions monosodium phosphate monohydrate that probably decomposes at about 200C.

More recently, patents dealing with film covered apertured cigarette wrappers issued as Tamol US. Pat. Nos. 3,511,247 and 3,526,904. The earlier patent teaches the use of a white cellular thermoplastic resin having microscopic voids' throughout covering the apertures. The patent indicates that such a film permits improved opening of the holes by heat and at a much ever, with respect to both of. these disclosures, the holes would not always open or opened ineffectively under conditions of use. To approach the desired objectives in Tamol, a critical feature was to select the proper film thickness for the particular wrapper thickness and the tobacco used and to avoid any variations of the polymer film' to insure the holes would open in the prescribed manner.

The present invention is an improvement over these prior disclosures in that while a polymeric film is used to cover the apertures of cigarette wrappers which eventually is opened to admit air after a period of smoking, the film is chemically treated and modified in its structure after it is applied to the wrapper, giving it characteristics that substantially expedite and insure the removal of the film by the smoke action, regardless of the film thickness or thetype of wrapper or the tobacco used.

SUMMARY OF THE INVENTION The present invention relates to a smoking product, and more particularly to a cigarette or other smoking article utilizing a combustible wrapper. The wrapper is normally porousor specifically provided with apertures, these being covered by a degradable polymeric film. Degradation of the film produces partial chain scission thereby hastening and facilitating the removal of the film over the apertures by smoke components when the tobacco is smoked. The degradation of the film is carried out by chemically treating the film with an oxidizer and free-radical generator such as benzoyl peroxide.

DESCRIPTION OF THE INVENTION The present invention relates 'to an apertured wrapper for a tobacco product such as a cigarette, and more particularly to a specifically treated film used to cover the wrapper and the pores or apertures therein.

It is an object of the present invention to obtain a more certain, controlled dilution of the smoke of a cigarette or the like with air admitted through special film coated apertures in the tobacco wrapper.

It is a further object of the present invention to provide a film coating over wrapper apertures so designed as to permit its easy removal by smoke action.

It is a still further object of the invention to make possible a reduction in the delivery per puff after early puffs and also in total delivery.

These and other objectives will become evident in the following description of the invention.

The objects of the present invention may be realized by treating a cigarette wrapper or other combustible tobacco wrapper having spaced openings or apertures with a polymeric material capable of forming a thin but continuous film over the wrapper when dry and containing a degradation agent dispersed therein. The agent is such as to cause at least partial chain scission of the polymeric film The resulting degraded film is then capable of quick and certain breakdown by smoke components during the smoking operation, thereby providing the necessary, positive openings for ventilation and smoke dilution at the time it is most desired.

Any polymeric or resinous material capable of forming a continuous, thin, degradable film on a tobacco wrapper in any thickness up to that of the wrapper itself may be used. A polymer material is used that is degradable and can be applied to form a continuous film without breaks when spread thin, that is, when spread on the wrapper to a thickness from 3 to 60 microns, preferably from about 5 to 15 microns thick.

Polymeric substances that may be used for this purpose are polyalkylene oxides, i.e., polyethylene or polypropylene oxides, polyvinyl alcohol or copolymers containing butadiene or isoprene units. Natural gums or resins such as dextrins, pectins, guar gum, tragacanth or gum arabic may also be used, although the easily controlled characteristics of synthetic polymers are preferred. Of these, polyethylene oxide of high molecular weight, in excess of 100,000 molecular weight is a preferred film-forming agent. More specifically, a polymeric material having a molecular weight of about 150,000 to about 600,000 is preferred although polymers of up to 5,000,000 molecular weight may be used.

The preferred polymers have the general formula:

HO( -C H,,O ),,H where x is an integer of about 1,600 to about 120,000, preferably representing an integer of about 3,400 to about 14,000. The polymer may be prepared by known methods, for example, as described in U.S. Pat. No. 3,5 26,904. A particularly suitable polymeric material is sold by Carbide and Carbon Chemicals Corp. under the trade name Polyox. Resin grades are usually assigned with grades N-80 to N-3000 representing the particular molecular weights of the resin, namely, materials of 150,000 mol. wt. and 600,000 mol. wt., respectively, being preferred.

The above-mentioned polymers may be used by themselves or may be modified with plasticizers, emulsifiers, non-ionic surfactants or other additives to improve the coating action or the type of coating, or merely for ease in applying the polymer coating to the wrapper. One type of modified polymeric resin that is preferred is the above-described Polyox polyethylene oxide having a molecular weight in the general range mentioned above to which has been added from 2 to percent by weight of a nonylphenoxy polyethylene oxide of 800 to 2,000 molecular weight as a non-ionic surfactant or plasticizer. A composition of this nature is sold under the trade name Tergitol by Carbide and Carbon Chemicals Co. However, other surfactants that are known to be compatible with the particular resin may be used.

To carry out the process of the invention, the polymeric material is dispersed or solubilized in an inert organic liquid or solvent for the polymer with or without such additives or modifiers as indicated above. Prior to applying the solution or dispersion to the perforated wrapper, a polymeric degradation agent is added and the solution is then applied to the perforated wrapper material by any known coating procedure capable of producing a relatively even continuous coating or thin layer on a thin wrapper base. One coating method is by knife-coating the coating solution on to the perforated wrapper. Another method utilizes roller coating. The wrapper itself is preferably the usual thin cigarette paper having pores similar in size and number as described in Tamol, U.S. Pat. No. 3,526,904, or

Figge, U.S. Pat. No. 2,993,647, to which reference had previously been made. However, cigarette wrappers having about to 200 pores per inch with pore sizes of about 0.005 to about 0.01 inch produce effective results.

After the coating is applied over the perforated wrapper, it is dried either under atmospheric conditions or under higher temperature conditions, for example, by heating, using hot air in a single or series of stages or by infrared or other heat-inducing means.

In order to bring about the essential feature of invention, namely, the degradation of the polymer or resin which is considered to result in substantial chain scission of the polymer, .an organic or inorganic oxidant/free-radical generator is added to the polymer before it is applied to coat the cigarette wrapper. Substances known to be free-radical generators or oxidizers such as the peroxides, the persulfates and certain azo compounds are useful for degrading the polymeric film. These substances are capable of freeradical generation at a controlled rate and at substantially room temperature. To obtain the degradation effect of such compounds, the oxidizing agent or freeradical generator is incorporated in the polymeric coating solution just prior to applying the coating solution to the perforated wrapper, using about 1 to about 10 percent by weight of the resin content. The preferred amount of oxidizer additive would be in the range of about 2 to 5 percent. At this concentration, the attack of the free-radicals on the resin is too slow to affect the coating process, but would normally occur over the time occupied by the making, shipping and storage of the final smoking product, so by the time the latter reaches the market, the desired degradation is substantially complete.

It should be noted that at the higher concentrations in the ranges given above, the degradation will take place at a shorter period of time, for example, in about 24 hours or even less if so desired for a polymeric film of 150,000 to 600,000 molecular weight and 5 to 10 microns thick. In general, one would use a higher concentration of free-radical material if the thickness of the film and the molecular weight was in the higher end of the stated ranges. It should also be noted that a greater degree of degradation, and therefore, a quicker rate of opening could be obtained by using higher concentrations of such oxidant/free-radical generators. Such manipulation of the various factors involved as indicated here would be apparent and within the expected skill of the operator.

Among the more active and effective known oxidizers and free-radical generators may be mentioned peroxides such as benzoyl peroxide which is the preferred degradation agent, acetyl peroxide, and decanoyl peroxide. With respect to persulfates, potassium and ammonium persulfate are contemplated, as are also specific azo compounds such as azoxybenzene, azobisisobutyronitrile and azodicarbonamide. These substances are deemed equivalent in their ability to act as oxidizers and/or free-radical generators capable of degrading the polymeric material utilized here, although as indicated above, benzoyl peroxide is the preferred agent.

The following examples are illustrative.

EXAMPLE 1 oxide (mol. wt. 150,000). To a portion of each of these solutions (four portions in all) was added, just before coating, benzoyl peroxide at 2.0 percent by weight of the resin content. Perforated cigarette paper having 0.010 X 0.014 inch holes, 154 per inch of length was knife-coated with the four solutions. The dried wrappers having an average film thickness of about to 12 microns were used to make filter cigarettes with a commercial filler. These cigarettes were smoked by machine approximately 2% weeks after manufacture.

The results of smoking these cigarettes by machine with measurement of TPM delivery puff-by-puff are shown in Table I. The method used was that described by Wartman, Cogbill, and Harlow, Analytical Chem. 31, 17054709 (1958), and the machine was that disclosed by W. F. Mutter in US. Pat. No. 3,433,054 granted Mar. 18, 1969.

TABLE 11 Cigar- Cigar- Cigar- Cigarem: one am: ette 1 2 3 4 benzoyl peroxide 1.0 2.0 3.0 5.0 TPM Puff 190 1.9 1.5 1.4 1.2 2 2.1 1.9 1.8 1.8 3 2.4 2.1 1.9 1.8 4 2.4 1.7 1.7 1.6 5 2.1 1.6 1.4 1.4 6 2.3 1.7 1.3 1.4 7 2.4 1.9 1.5 p 1.6 8 2.8 2.0 1.6 1.7 9 2.9 2.3 1.9 2.1 10 2.1 2.4

From the results as shown in Table II, it is concluded that 2 wt. benzoyl peroxide provided sufficient film modification to permit hole opening during smoking to yield a relatively constant TPM delivery on a per puff basis. It will also be noted that 3 or 5 percent by weight of benzoyl peroxide provided significantly greater reduced delivery after the early puffs.

TABLE I Control No. 1 Control No. 2 Control Ci arette Perforated Perforated Perforated Perforated Nonperforated. Coating 5505% Tergitol" 7505% Tergitol 805% 'Ierglto.... 805% Tergitol None. Additive None.............. 2% benzoyl peroxide.. None 2% benzoyl peroxide... D PIM Putt No.1

EXAMPLE 2 Four coating solutions were prepared as described in Example 2 using 8.5 g. of Polyox N-3000 polyethylene oxide (molecular weight about 6000,000) and 0.42 g. of Tergitol NP-40. To consecutive solutions was added, just before coating, benzoyl peroxide at 1.0, 2.0, 3.0

and 5.0 wt. respectively, of the resin content. Perforated cigarette paper as described in Example 1 was knife-coated with the four solutions and the dried wrappers having an average film thickness of 10 to 12 microns were used to make filter cigarettes with a commercial filler. The cigarettes were smoked by machine as described above within 1 week of making and gave TPM delivery values as listed in Table II.

EXAMPLE 3 A coating solution was prepared in the same manner as described in Example 1 using 8.5 grams of Polyox N- 3000 polyethylene oxide (molecular weight of about 600,000) and 0.42 grams of Tergitol NO-40. An identical solution was prepared to which was added, .just before coating, benzoyl peroxide at 3.0 wt. of the resin content. Perforated cigarette paper as described in Example l was knife-coated with each of these solutions and the dried wrappers having an average film thickness of about 10 to 12 microns were used to make filter cigarettes with a commercial filler. The cigarettes were machine smoked in the manner described above within 1 day after making, giving TPM delivery values as shown in Table III.

From the results as given in Table III, it is concluded that for this grade of polyethylene oxide, 3 percent benzoyl peroxide provided film modification to permit hole opening within 24 hours after making. This is demonstrated by reduced TPM delivery on a per puff basis from pufi number 4 on.

The invention that is claimed is:

l. A cigarette wrapper or the like comprising a combustible material having apertures therein, and a resin selected from the group consisting of polyalkaline oiides, polyvinyl alcohol and copolymers thereof containing butadiene or isoprene units, and natural gums and resins coating of about 3 to 60 microns thick over said apertures said resin being degraded after being in intimate contact with an oxidizer/free-radical generating degradation agent in an amount of about 1 to 10 percent by weight based on the resin, said agent being dispersed throughout the resin coating.

bustible material having apertures therein and a benzoyl peroxide degraded polyethylene oxide filling material normally closing said apertures, said film having a thickness of about 5 to 15 microns, the degraded film permitting rapid breakdown by smoke components.

3. The product of claim 2, inwhich the wiyei'fiieie oxide polymer has a molecular weight of about 150,000 to about 600,000.

4. The process comprising mixing a polyethylene Patent No. 3,705,588 Dated December 12, 1972 Inventor(s) Ronald A. Tamol and Leo F. Meyer It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the Abstract, line 4, "polyalkalene" should be polyalkylene Column 1', line 25, the letter "b" should be deleted.

, In Table I, in first- "Control" column, "550-5Z, Tergito'l" should be 750-570 Tergitol In Table I, in same "Control" column, "1.1" should be 2.1 -e

V In Table l, in second "Control" column, "BO-5% Tergito" should be 80- 5"/ Tergitol In Footnote after "300,000", insert and 150,000 -e.

Column 5, line 57, "6000,000" should be 600,000 -e..

In Table II, first column, "TPM Puff 190" should be TPM Puff 1 Claim 1, line 3, "polyalkaline" should be po'lyalkylene Signed and sealed this 9th day of April. l97l (SEAL) Attest:

EDWAPJJ PLFIETCHER,JR. C. MARSHALL DANN Attesting Officer Commissione r of Patents 

2. A cigarette wrapper of the like comprising a combustible material having apertures therein and a benzoyl peroxide degraded polyethylene oxide filling material normally closing said apertures, said film having a thickness of about 5 to 15 microns, the degraded film permitting rapid breakdown by smoke components.
 3. The product of claim 2, in which the polyethylene oxide polymer has a molecular weight of about 150,000 to about 600,000.
 4. The process comprising mixing a polyethylene oxide solution with about 2 to 5 percent by weight of an oxidizer, free-radical generating degradation agent, coating the resin solution on a tobacco wrapper having spaced apertures therein, covering said apertures and said wrapper with a thin continuous film of resin, and then drying the coated wrapper, the dried film being 5 to 15 microns thick.
 5. The process of claim 4, in which the degradation agent is benzoyl peroxide and the degradation is carried out over a period of at least 24 hours. 